Chemiluminescent smokes



United States Patent 3,551,342 CHEMILUMINESCENT SMOKES Urho AlbertLehikoinen, Detroit, Mich., assignor to Ethyl Corporation, New York,N.Y., a corporation of Virginia No Drawing. Filed June 29, 1967, Ser.No. 649,835 Int. Cl. C09k 3/00 US. Cl. 252-488.? 16 Claims ABSTRACT OFTHE DISCLOSURE Chemiluminescent smoke, that is, a smoke visible both byday and night, is produced when a composition consisting essentially of(a) an aluminum alkyl, (b) an ether or an amine complexing agent, and(c) an imidazole, is contacted with air and water.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION An improvedsmoke-producing material is provided by a composition consistingessentially of (a) a trialkyl aluminum or an aluminum alkyl hydridewhich is previously complexd with (b) a complexing agent selected from amonoether, di-

ether, or a triether or a tertiary amine, and admixed with (c)animidazole.

When the above composition comes in contact with air and water, a cloudof smoke visible both by day and night is formed,

PREFERRED EMBODIMENTS This invention pertains to chemiluminescent smokescontaining an alkyl aluminum and an imidazole.

The particular feature of the smoke produced by a composition of thisinvention is the luminescent property; that is, visibility both by dayand night.

An object of this invention, which is to prepare a nightvisible smoke,is satisfied by providing compositions conh sisting essentially of (a)an aluminum alkyl having the formula RRR"Al or an alkylaluminum hydridehaving the formula RRAlH or mixtures of said hydrides and/or aluminumalkyls wherein R, R and R" are alkyl radicals of 1 to 4 carbon atoms,said aluminum compound being complexed with a chemically equivalentamount of (b) a complexing agent selected from (1) an ether having up toabout carbon atoms and 1 to 3 ether-oxygen linkages, said ether beingfree of acetylenic bonds, and (2) a tertinary amine having up to about24 "ice carbon atoms, the complexed aluminum alkyl being admixed with(c) from 20 to weight percent of an imidazole having up to about 21carbon atoms.

These compositions yield chemiluminescent smoke clouds when they come incontact with air or any other oxidizing agent and water. The method ofwater mixing is not critical. The smoke agent may be injected underneaththe surface of water to yield a cloud of chemiluminescent smoke abovethe surface of the water. Alternatively, the smoke agent can be merelyadmixed with water by shaking the agent and water in a vessel. Anothermethod for contacting the agent with water is to introduce a stream ofthe agent into a water spray.

Although a larger and more intense smoke cloud is produced when thecomposition of this invention is reacted with large qnantities of water,satisfactory results are also obtained when the only water present isthe Water vapor normally present in the air or the water of hydrationpresent in a compound such as an alum, when such a compound is admixedwith the smoke-producing composition.

One essential ingrcdient in the smoke compositions of this invention isan aluminum compound of the types given above. Preferably, all alkylradicals bonded to the aluminum atom are identitcal. Most preferably,these alkyl radicals are solely composed of carbon and hydrogen and haveup to four carbon atoms. Typical examples of alkyl aluminums which areapplicable in this invention are trimethylaluminum, triethylaluminumdiethylaluminurn hydride, methyldiethylaluminum, triisopropylaluminum,tri-sec-butylaluminum, and the like.

For the purposes of this invention, the aluminum alkyl is complexed witheither an ether or an amine. A wide variety of ethers can be employed.The exact nature of the ether is not critical provided it can complexwith the aluminum compound and is devoid of substituent groups whichlead to deleterious side effects. Preferably, the ethers have less thanabout 15 carbon atoms. They may have one, two, or three or more etherlinkages, -O. More preferably, the ethers employed in this invention arefree from acetylenic linkages.

Monoethers which may be employed have the formula wherein R and R areindependently selected from alkyl groups having 1 to 4 carbon atoms;aryl groups such as phenyl and tolyl; alkenyl groups of 3 to 5 carbonatoms such as allyl; cycloalkyl groups such as cyclohexyl, and the like.Typically preferred ethers of this type are diethyl ether, isopropylether, ally] ether, phenyl ether, benzyl ether, benzyl ethyl ether,a-methylbenzyl ether, and the like. Cyclic monoethers can be employed. Ahighly preferred ether which is used in this invention istetrahydrofuran. Biethers, that is, ethers which contain two etheroxygen linkages, can be employed in this invention. Typical ethers ofthis type which may be employed are ethylene glycol diethyl ether,ethylene glycol dibutyl ether, ethylene glycol diamyl ether, and thelike.

Triethers (sometimes referred to as tridentate ethers) which may beemployed in this invention preferably have the ether oxygen linkagesseparated by two carbon atoms; that is, ethylene radicals. Typicalethers of this type which can be employed in this invention arediethyleneglycol dimethylether, diethyleneglycol diethylether, anddiethyleneglycol dibutylether.

As mentioned above, aluminum alkyls can also be complexed with an amine.A wide variety of tertiary and hindered secondary amines can beemployed. The exact nature of the amine is not critical, provided it cancomplex with the aluminum compound and is devoid of substituent groupswhich lead to deleterious side effects. Any tertiary amine may beemployed. but the practical reasons, tertiary amines having up to aboutcarbon atoms are preferred. Illustrative examples of applicable aminesare N,Ndimethylaniline, dicyclohexylamine, N-benzyl- N ethylaniline,N-benzyl-N-ethyl-m-toluidine, dibenzylamine, ditolylamine,diisobutylamine, tert-butylamine, N, N-diethylaniline, tribenzylamine,tri n octylamine, triphenylamine, N,N-dimethylbenzylamine,dodecyldimethylamine, N,N-di-methyl-o, m, and p-toluidines,N,N-diethyl-o, m, and p-toluidines, N,N-ethylmethylaniline and the like.Preferably, the amines are selected from hexamethylene tetramine andtetra(lower alkylene)diamines and hexa(lower alkylene)diamines such attetramethylenediamine, tetraethylenediamine, tetrapropylenediamine,tetrabutylenediamine, hexamethylenediamine, hexaethylenediamine,hexapropylenediamine, hexabutenediamine, and the like.

Although the above-described complexing agents are k preferred, othercomplexing agents may also be employed. Examples of such additionalagents are thioethers, organic phosphines such as tributylphosphine,trioctylphosphine, and triphenylphosphine, and metal salts, especiallyalkali and alkaline earth metal salts such as lithium chloride andtriethylaluminium-sodium fluoride complex.

The complexing of the alkyl aluminum with an ether or an amine abovedescribed is readily carried out by simply mixing the complexing agentand the alkyl aluminum under anhydrous conditions and in the presence ofan inert atmosphere. Typically, nitrogen is used to provide the inertatmosphere. However, other inert gases such as argon and neon can beemployed, if desired. Best results are obtained when all of the alkylaluminum is complexed. When using a monoether, at least one mole ofether is employed for each mole of alkyl aluminum. Similarly, when adiether is employed, at least one-half mole of ether is employed foreach mole of alkyl aluminum. Furthermore, with tridentate ethers themole ratio of ether to aluminum is at least 1 to 3. When using adiamine, at least one-half mole of amine is employed for each mole ofalkyl aluminum. Similarly, when a tetramine is employed, at leastone-quarter mole of amine is employed for each mole of alkyl aluminum.

It is not necessary to employ an exactly chemiequivalent amount of acomplexing agent and alkyl aluminum. An excess of ether or amine can beused. When volatile complexing agents such as diethyl ether areemployed, an excess of the complexing agent may be beneficial. In someinstances, it appears that the presence of an excess of a complexingagent yields a larger smoke cloud. Consequently, it is convenient toemploy up to 5 equivalents of a complexing agent for each equivalent ofalkyl aluminum.

Another important ingredient in the compositions of this invention is animidazole. Illustrative examples of imidazoles and related compoundsuseful in this invention are benzimidazole,2-benzimidazolecarbamonitrile, 2-benzimidazolylacetonitrile,4,5-diphenylimidazole, 2,5-dimethylimidazole, 5 isobutylimidazole, 5ethyl-Z-hexylimidazole, 2,4,5-triphenylimidazole, 2-tolylimidazole,2-ethyl- S-methylimidazole, 2 methylbenzimidazole, 2phenylbenzimidazole, and the like.

After the alkyl aluminum is complexed, it is then mixed with an amountof an imidazole which is sufiieient to yield a final preparationcontaining from to 50 weight percent of an imidazole of the typedescribed above. The mixing of the complex with an imidazole compound isconveniently carried out using simple mixing procedures. As in the caseof complexing, a slight amount of heat may be beneficial; that is, itmay be desirable to heat up the mixture to a temperature within therange of 30- 50 C.

As pointed out above, the chemiluminescent smoke formulations of thisinvention yield smoke clouds which are visible at night when contactedwith air and water. The water need not be pure; natural waters such aslake, river or sea water can be employed as can muddy or wet earth. Inaddition, the water may be chemically bound; that is, waters ofhydration. When using chemically-bound water, a compound whichpreferentially contains a large amount of waters of hydration isemployed. Preferred compounds containing waters of hydration are alums.Typical alums which may be used are described on pages 196-199 of the8th edition of Langes Handbook of Chemistry, Handbook Publishers, Inc.,Sandusky, Ohio (1952).

To further illustrate the invention, the following nonlimiting examplesare presented. Unless otherwise indicated, all parts are by weight.

EXAMPLE 1 Two hundred and twenty-six milliliters of diethyl ether isadmixed with 290 ml. of triethylaluminum under anhydrous conditions andin the presence of a nitrogen atmosphere. This yields a diethylether-triethylaluminum complex. To the resultant mixture is added 290grams of 2,4,5-triphenylimidazole.

The resultant smoke formulation yields a chemiluminescent smoke whenadmixed with water in air. For example, equal volumes of agent and waterwhen admixed together yield a chemiluminescent smoke. Furthermore, sucha smoke is produced when one volume of agent is injected under thesurface of approximately 10 volumes of water without stirring. Thirdly,the formulation yields a chemiluminescent smoke when 50 parts of theformulation are added to parts of lCr (SO K2804 EXAMPLE 2 Following theprocedure of Example I, smoke formulations containing equimolar amountsof diethyl ether and triethylaluminum and 40 percent of 2-benzimidazoleare prepared. When these formulations are admixed with water,chemiluminescent smokes are produced.

Similar results are obtainned when 2-benzimidazole is replaced by2-benzimidazolecarbonitrile, 4,5 diphenylmidazole, andS-isobutylamidazole.

EXAMPLE 3 Equimolar complexes of tetrahydrofuran with triethyl aluminumand dioxane with triethylaluminum are prepared using the procedure ofExample 1. They are admixed with sufiicient quantities of2,5-dimethylimidazole to yield formulations containing 20, 30, 40 and 50weight percent of 2,5-dimethylimidazole.

EXAMPLE 4 Seven parts of hexamethylenetetramine is admixed with 22.8parts of triethylaluminum under anhydrous conditions and in the presenceof a nitrogen atmosphere. This yields an amine-triethyl aluminumcomplex. To the resultant complex is added 0.9 part of tetrahydrofuranand then 20 parts of 2-tolylimidazole.

This smoke agent has the following formulation (in weight percent):

Hexamethylenetetraminel 3 8. Triethylaluminum45 .0.2-tolylimidazole-39.5. Tetrahydrofuran-1.8.

The tetrahydrofuran is not a critical ingredient but aids in thesolubilization of the hexamethylenetetramine. Usually, about 1 to 3weight percent of such a solubilization agent is efficatiously employed.Besides tetrahydrofuran, ethers described above as complexing agents maybe employed as solubilizing agents.

Similar results are obtained when in the above examplehexamethylenetetramine is substituted with tetraethylenediamine,N,N,N,N'-tetraethyl ethylenediarnine, N,N,N',

N'-tetrabutyl ethylenediamine; triethylaluminum is substituted withtriisopropylaluminum, tributylaluminium, and diethylaluminum hydride;2-tolylimidazole is substituted with Z-methylbenzylimidazole andZ-phenylbenzimidazole.

Following the procedure of Examples 1 and 3, smoke agents containingethyl ether, phenyl ether, diethyl Carbitol, anisole, p-chloroanisole,veratole, ut-methylbenzyl ether, and benzyl ether are prepared.

The smokes of this invention are visible at night have many utilities.For example, they can be employed for marking purposes in sea rescues,Similarly, they may be used to direct artillery fire or aerialbombardments.

An important aspect of this invention is that the smokes are visible byday and at night. Hence, they have daytime and nighttime utilities.Accordingly, the compositions of this invention have a dual function. Itis believed that this dual function is not accomplished by smokes andflares presently in use.

Having fully described the novel compositions of this invention, theirmethod of preparation, and their utility, it is desired that the scopeof this invention be solely limited by the lawful extent of the appendedclaims.

What is claimed is:

1. A chemiluminescent smoke composition being prepared by mixing (a) analuminum alkyl having the formula RRR"Al wherein R, R and R" are alkylradicals of 1 to 4 carbon atoms, said aluminum alkyl being complexedwith at least a chemically equivalent amount of (b) a complexing agentselected from the group consisting of (i) an unsubstituted ether havingup to about 15 carbon atoms and l to 3 ether-oxygen linkages, said etherbeing free of acetylenic bonds, (ii) tertiary amine having up to about15 carbon atoms, the complexed aluminum alkyl being admixed with (c)from 20 to 50 weight percent of an imidazole selected from the groupconsisting of imidazole and benzimidazole and lower C alkyl, phenyl andtolylsubstituted imidazole and benzimidazole.

2. A smoke composition of claim 1 wherein the aluminum alkyl istriethylaluminum.

3. A smoke composition of claim 2 wherein said imidazole is selectedfrom the group consisting of phenyl and tolyl substituted imidazole.

4. A smoke composition of claim 2 wherein said complexing agent isdiethylether.

5. A smoke composition of claim 2 wherein said complexing agent istetrahydrofuran.

6. A smoke composition of claim 2 wherein said complexing agent isdioxane.

7. A smoke composition of claim 2 wherein said complexing agent ishexamethylenetetramine.

8. A smoke composition of claim 2 wherein said complexing agent isN,N,N',N-tetra(lower alkyl) ethylenediamine, wherein said lower alkylgroups have from 1 to 4 carbon atoms.

9. A method for producing a chemiluminescent smoke, said methodcomprising contacting a smoke composition of claim 1 with air and water.

10. A method of claim 9 wherein said water is from an alum having theformula [Cr (SO,) -K SO -24H O].

11. A smoke composition of claim 2 wherein said imidazole is selectedfrom the group consisting of 2,5-dimethylimidazole,5-ethyl-2-hexylimidazole, and 2-ethyl-5- methylimidazole.

12. A smoke composition of claim 2 wherein said complexing agent is anunsubstituted monoether having the formula:

wherein R and R are independently selected from alkyl groups having 1 to4 carbon atoms, phenyl, tolyl, alkenyl groups having 3 to 5 carbonatoms, and cyclohexyl groups.

13. A smoke composition of claim 12 wherein said imidazole is selectedfrom the group consisting of 2,5-dimethylimidazole,5-ethyl-2-hexylimidazole, and 2-ethyl-5- methylimidazole.

14. A smoke composition of claim 2 wherein said complexing agent is atertiary amine selected from the group consisting ofhexamethylenetetramine, tetra(lower alkylene)diamine, and hexafloweralkylene)diamine, said lower alkylene having from 1 to 4 carbon atoms.

15. A smoke composition of claim 7 wherein said imidazole is selectedfrom the group consisting of 2,5-dimethylimidazole,5-ethyl-2-hexylimidazole, and 2-ethyl-5- methylimidazole.

16. A smoke composition of claim 4 wherein said imidazole is2,5-dimethylimidazole.

References Cited UNITED STATES PATENTS 3/1967 Sherman 424-40 9/1968Gluckstcin et al. 252305 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 5,55 5 Dated December 29, 1970 Inventor) UrhoAlbert Lehikoinen It 10 certified that errcr appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 5, line L9, (Claim l, line 1), "Claim 2" should read Claim 12Column 6, line 3, (Claim 7, line 1), "Claim 2" should read Claim 1% line5, (Claim 8, line 1), Claim should read Claim 14 bit-mad 'MQ SEALED Ma61971

